Several recent reports have emphasized the potential advantages of tissue and bone selective dual-energy images for improving lesion detection and characterization. Systems investigated have included those using scanned slit detector systems and those employing conventional large-area receptor geometry. Failure to correct for x-ray scatter and beam hardening in the latter systems leads to nonuniformity of material selection and in particular, poor visualization of the thoracic spine. In addition, image noise has been a problem. We proposed to investigate a dual-energy radiographic system involving the following key elements. 1. Gadolinium prefiltration to produce a spectrum with low and high energy peaks. 2. A detector consisting of four sequential BaFBr storage phosphor plates which detect images of steadily increasing energy from a single radiographic exposure. 3. Spatially variable energy dependent scatter corrections. 4. Spatially variable beam hardening corrections. 5. An adaptation of a new dual-energy noise reduction algorithm recently introduced by Kalender for dual-energy CT. The proposed research includes optimization of the data acquisition system and image processing software, and five clinical studies which include: 1) pulmonary nodule detection, 2) evaluation of intrathoracic airways, 3) evaluation of intrathoracic bone fractures, 4) evaluation of the genitourinary system, and 5) comparative evaluation of anatomical features.